Crystal structure and Temperature-Dependent Luminescence Characteristics of KMg(4)(PO(4))(3):Eu(2+) phosphor for White Light-emitting diodes

The KMg(4)(PO(4))(3):Eu(2+) phosphor was prepared by the conventional high temperature solid-state reaction. The crystal structure, luminescence and reflectance spectra, thermal stability, quantum efficiency and the application for N-UV LED were studied respectively. The phase formation and crystal structure of KMg(4)(PO(4))(3):Eu(2+) were confirmed from the powder X-ray diffraction and the Rietveld refinement. The concentration quenching of Eu(2+) in the KMg(4)(PO(4))(3) host was determined to be 1mol% and the quenching mechanism was certified to be the dipole–dipole interaction. The energy transfer critical distance of as-prepared phosphor was calculated to be about 35.84Å. Furthermore, the phosphor exhibited good thermal stability and the corresponding activation energy ΔE was reckoned to be 0.24eV. Upon excitation at 365nm, the internal quantum efficiency of the optimized KMg(4)(PO(4))(3):Eu(2+) was estimated to be 50.44%. The white N-UV LEDs was fabricated via KMg(4)(PO(4))(3):Eu(2+), green-emitting (Ba,Sr)(2)SiO(4):Eu(2+), and red-emitting CaAlSiN(3):Eu(2+) phosphors with a near-UV chip. The excellent color rendering index (Ra = 96) at a correlated color temperature (5227.08K) with CIE coordinates of x = 0.34, y = 0.35 of the WLED device indicates that KMg(4)(PO(4))(3):Eu(2+) is a promising blue-emitting phosphor for white N-UV light emitting diodes (LEDs).